Adapt to new ConstantExpr in Clang trunk towards Clang 8

After <https://reviews.llvm.org/D53921> "Compound literals, enums, et al require
const expr" (making use of ConstantExpr recently introduced with
<https://reviews.llvm.org/D53475> "Create ConstantExpr class",
CompilerTest_compilerplugins_clang started to fail with

> [CPT] compilerplugins/clang/test/unnecessaryparen.cxx
> error: 'error' diagnostics expected but not seen:
>   File /data/sbergman/lo-clang2/core/compilerplugins/clang/test/unnecessaryparen.cxx Line 35: parentheses immediately inside case statement [loplugin:unnecessaryparen]
> error: 'error' diagnostics seen but not expected:
>   File /data/sbergman/lo-clang2/core/compilerplugins/clang/test/unnecessaryparen.cxx Line 35: unnecessary parentheses around identifier [loplugin:unnecessaryparen]
> 2 errors generated.

Change-Id: Iebcfcd9af30e26df02819fbffb105599fa6a1701
Reviewed-on: https://gerrit.libreoffice.org/63285
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/compilerplugins/clang/unnecessaryparen.cxx b/compilerplugins/clang/unnecessaryparen.cxx
index 1a26ed21c7fb..b2ad2951ec90 100644
--- a/compilerplugins/clang/unnecessaryparen.cxx
+++ b/compilerplugins/clang/unnecessaryparen.cxx
@@ -15,6 +15,9 @@
 #include <unordered_set>
 
 #include <clang/AST/CXXInheritance.h>
+
+#include "config_clang.h"
+
 #include "compat.hxx"
 #include "plugin.hxx"
 
@@ -52,6 +55,11 @@ Expr const * ignoreAllImplicit(Expr const * expr) {
                 expr = ce->getImplicitObjectArgument();
             }
         }
+#if CLANG_VERSION >= 80000
+        else if (auto const e = dyn_cast<ConstantExpr>(expr)) {
+            expr = e->getSubExpr();
+        }
+#endif
         if (expr == oldExpr)
             return expr;
     }